Dawkins credited football with giving him an opportunity to obtain a college degree -- he graduated from Arizona before transferring to Indiana -- but acknowledged he hasn't enjoyed the sport in recent years.
"The most important thing to me though has been the joy that the game always brought me," Dawkins wrote. "Over the last couple years I lost touch with that joy. I respect and love the game, but I have lost touch with it. I am not too proud to admit that I needed help.
"I am grateful for the sports psychology team at both Arizona and Indiana for helping me at some of the lowest points in my life. The game has [been] getting me depressed and hurting my well-being."
Indiana coach Tom Allen announced last week that sophomore quarterback Peyton Ramsey had won the starting job, and on Monday, the coach said Dawkins would leave the program.
"We wish him nothing but the very best," Allen said. "He's a fine young man."
Dawkins was the starter at Arizona in 2016 and remained in that role to begin the 2017 season, before the emergence of Khalil Tate. In 22 games for the Wildcats, Dawkins threw for 2,418 yards and rushed for 1,582 yards.
"As my mental health is deteriorating I have decided to take a break from the game," he wrote. "I know now that I need to take care of ME. I need to make myself important. I have not properly taken care of myself.
"Do I know what's next? Of course not, but I do know God has a plan that is way bigger than any plans I could ever imagine for myself."